Stimulate/components/signal_generators/src/sine_generator.c

#include "sine_generator.h"
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "esp_log.h"

// 初始化正弦波生成器
void sine_generator_init(sine_generator_t *generator, float sample_rate) {
    if (generator == NULL) return;
    
    memset(generator, 0, sizeof(sine_generator_t));
    
    // 设置默认参数
    generator->frequency = 200.0f;      // 默认200Hz正弦波
    generator->amplitude = 1.0f;        // 幅值1.0V
    generator->sample_rate = sample_rate;
    generator->is_running = false;
    
    // 查找表参数
    generator->sine_lookup_table = NULL;
    generator->table_size = 0;
    generator->table_index = 0;
}

// 设置正弦波频率
void sine_generator_set_frequency(sine_generator_t *generator, float frequency) {
    if (generator == NULL) return;
    
    // 限制频率范围
    if (frequency < 0.1f) frequency = 0.1f;
    if (frequency > 10000.0f) frequency = 10000.0f;
    
    generator->frequency = frequency;
    
    // 如果已经运行，重新生成查找表
    if (generator->is_running) {
        sine_generator_generate_lookup_table(generator);
    }
    
    ESP_LOGI("SINE_GEN", "Sine wave frequency set to: %.1f Hz", frequency);
}

// 设置幅值（直接输入mV值，内部自动转换为DAC输出值）
void sine_generator_set_amplitude(sine_generator_t *generator, float amplitude_mv) {
    if (generator == NULL) return;
    
    // 硬件衰减系数：约38倍 (根据实际测量：0.132V → 5mV)
    // 对应关系：amplitude(V) × 38 ≈ 示波器显示值(mV)
    const float attenuation_factor = 38.0f;
    
    // 将mV除以衰减系数得到DAC输出值
    float dac_amplitude = amplitude_mv / attenuation_factor;
    
    generator->amplitude = dac_amplitude;
    
    // 如果已经运行，重新生成查找表
    if (generator->is_running) {
        sine_generator_generate_lookup_table(generator);
    }
    
    ESP_LOGI("SINE_GEN", "Sine wave amplitude set to: %.1f mV", amplitude_mv);
}

// 开始生成
void sine_generator_start(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    generator->is_running = true;
    generator->sample_count = 0;
    
    // 生成查找表
    sine_generator_generate_lookup_table(generator);
    
    ESP_LOGI("SINE_GEN", "Sine generator started: %.1f Hz, %.1f mV", 
             generator->frequency, generator->amplitude * 38.0f);
}

// 停止生成
void sine_generator_stop(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    generator->is_running = false;
    ESP_LOGI("SINE_GEN", "Sine generator stopped");
}

// 重置生成器
void sine_generator_reset(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    generator->sample_count = 0;
    generator->table_index = 0;
}

// 获取下一个样本
float sine_generator_get_next_sample(sine_generator_t *generator) {
    if (generator == NULL || !generator->is_running) {
        return 0.0f;
    }
    
    // 使用预计算的查找表，超高速访问
    if (generator->sine_lookup_table != NULL && generator->table_size > 0) {
        // 从查找表获取预计算的值
        float sine_value = generator->sine_lookup_table[generator->table_index];
        
        // 更新索引，循环使用查找表
        generator->table_index = (generator->table_index + 1) % generator->table_size;
        generator->sample_count++;
        
        return sine_value;
    } else {
        // 如果查找表未初始化，使用实时计算（备用方案）
        float t = (float)generator->sample_count / generator->sample_rate;
        float sine_value = generator->amplitude * sinf(2.0f * M_PI * generator->frequency * t);
        
        // 添加偏置电压
        float offset = generator->amplitude;
        sine_value = sine_value + offset;
        
        // 限制在DAC有效范围内
        if (sine_value < 0.0f) sine_value = 0.0f;
        if (sine_value > 2.048f) sine_value = 2.048f;
        
        generator->sample_count++;
        return sine_value;
    }
}

// 生成正弦波查找表
void sine_generator_generate_lookup_table(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    // 释放旧的查找表
    sine_generator_free_lookup_table(generator);
    
    // 计算查找表大小：一个完整周期的样本数
    // 表大小 = 采样率 / 正弦波频率
    generator->table_size = (uint32_t)(generator->sample_rate / generator->frequency);
    
    // 确保表大小至少为1
    if (generator->table_size < 1) {
        generator->table_size = 1;
    }
    
    // 分配内存
    generator->sine_lookup_table = (float*)malloc(generator->table_size * sizeof(float));
    if (generator->sine_lookup_table == NULL) {
        ESP_LOGE("SINE_GEN", "Failed to allocate memory for sine lookup table");
        generator->table_size = 0;
        return;
    }
    
    // 预计算正弦波值
    for (uint32_t i = 0; i < generator->table_size; i++) {
        // 计算时间点
        float t = (float)i / generator->sample_rate;
        
        // 计算正弦波值
        float sine_value = generator->amplitude * sinf(2.0f * M_PI * generator->frequency * t);
        
        // 添加偏置电压
        float offset = generator->amplitude;
        sine_value = sine_value + offset;
        
        // 限制在DAC有效范围内
        if (sine_value < 0.0f) sine_value = 0.0f;
        if (sine_value > 2.048f) sine_value = 2.048f;
        
        generator->sine_lookup_table[i] = sine_value;
    }
    
    // 重置索引
    generator->table_index = 0;
    
    ESP_LOGI("SINE_GEN", "Generated sine lookup table: %u points, %.1f Hz", 
             generator->table_size, generator->frequency);
}

// 释放正弦波查找表
void sine_generator_free_lookup_table(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    if (generator->sine_lookup_table != NULL) {
        free(generator->sine_lookup_table);
        generator->sine_lookup_table = NULL;
    }
    
    generator->table_size = 0;
    generator->table_index = 0;
}

// 清理生成器（释放所有资源）
void sine_generator_cleanup(sine_generator_t *generator) {
    if (generator == NULL) return;
    
    generator->is_running = false;
    sine_generator_free_lookup_table(generator);
    
    ESP_LOGI("SINE_GEN", "Sine generator cleaned up");
}